We are used to measuring distance on the coordinate plane using a version of the Pythagorean theorem.D = sqrt((x1-x2)^2 + (y1-y2)^2).This is called a metric.What if we changed the way we measured distance?What if we measured distance according to how a taxicab would travel .... only north/south or east/west.This is a valid metric and results in some interesting geometric results.It forces us to think "outside the box."